Thermodynamics of Pyrrhotite (Fe 1−δ S) at the Temperature Range of 800°∼1100°C

For the better understanding and improvement of the smelting process, it is necessary to know the thermodynamic properties of the matters concerned with the process. In some metallurgical processes, the iron sulphide plays an important role, especially, in the smelting or sintering processes of copper and lead ores. It is, therefore, interesting to study the thermodynamic properties of pyrrhotite. Pyrrhotite is a solid solution whose sulphur contents range from 50.00 to about 58 at% at maximum(1). Rosengvist(2) studied carefully the phase relations of this system by utilizing the gaseous mixture of H2H2S. In the current study, the authors used the same gaseous mixture to determine the chemical potential of sulphur in pyrrhotite. Statistical thermodynamics has successfully been applied to the solid solutions of metal oxides whose compositions deviate from stoichiometry. The authors supposed that it would be similarly applicable to solid solutions of sulphides, for example, of iron, cobalt, etc. Thus, the present work was undertaken from the viewpoints of practical importance and theoretical interest of pyrrhotite.